Look... why you don't want to use a loop?! It's something that you can't avoid sometimes. The result you are looking for is weird, maybe you can work with tables and dict (new Matlab data type) instead of struct.
In "my solution" you have two loops! :)
% input
dataArray = [21,22,23,24,25,26,27,28,29,30];
structureOfIndexes.a1 = [2,8];
structureOfIndexes.a2 = [1,5,7];
% Loops... thanks God!
fn = fieldnames(structureOfIndexes);
for ii = 1:numel(fn)
tempValues = [];
for jj = 1:numel(structureOfIndexes.(fn{ii}))
idx = structureOfIndexes.(fn{ii})(jj);
tempValues = [tempValues, dataArray(idx:idx+2)];
end
resultStructure.(fn{ii}) = tempValues;
end
resultStructure
